A magnetic tunnel junction (MTJ) device is an integrated circuit component having two conductive magnetic electrodes separated by a thin non-magnetic tunnel insulator material (e.g., dielectric material). The insulator material is sufficiently thin such that electrons can tunnel from one magnetic electrode to the other through the insulator material under appropriate conditions. At least one of the magnetic electrodes can have its overall magnetization direction switched between two states at a normal operating write or erase current/voltage, and is commonly referred to as the “free” or “recording” magnetic electrode. The other magnetic electrode is commonly referred to as the “reference”, “fixed”, or “pinned” magnetic electrode, and has an overall magnetization direction which is not switched upon application of the normal operating write or erase current/voltage.
The free magnetic electrode and the fixed magnetic electrode are electrically coupled to respective conductive nodes. Electrical resistance between those two nodes through the free magnetic electrode, insulator material, and the fixed magnetic electrode is dependent upon the magnetization direction of the free magnetic electrode relative to that of the fixed magnetic electrode. Accordingly, a magnetic tunnel junction can be programmed into one of at least two states, and those states can be sensed by measuring current flow through the magnetic tunnel junction device. Other methods of reading may include a so-called “switch and detect” scheme.
Since magnetic tunnel junction devices can be “programmed” between two current-conducting states, they have been proposed for use in memory integrated circuitry. Additionally, magnetic tunnel junction devices may be used in logic, sensors, oscillators or other circuitry apart from or in addition to memory.